Carefully examine the placement of all your cables. It's possible that a single cable is picking up inteference from a nearby source.
Practically speaking you do not have a problem. From what you've written the noise is only apparent if you position your ear 1" away from the speaker. At that distance many if not a majority of systems will exhibit some noise.
Practically speaking you do not have a problem. From what you've written the noise is only apparent if you position your ear 1" away from the speaker. At that distance many if not a majority of systems will exhibit some noise.